(1) Field of the Invention
The present invention relates to a lead battery comprising as an active material a formation product of novel lead monoxide or its calcination product or a sulfuric acid paste thereof.
(2) Brief Description of the Prior Art
As the starting substance of an active material of a lead battery, there have heretofore been used so-called lead powder, litharge and minium. These starting substances of active materials have heretofore been commercially manufactured in the form of lead powder according to the ball mill method developed by Mr. Genzo Shimazu in 1925 or according to the molten flow method. According to the bal mill method, granules of metallic lead having a size of 20 to 25 mm are charged in a tube mill and air is blown into the tube. By friction and oxidation with oxygen in air, which is accompanied by generation of heat, so-called lead powder is peeled off from surfaces of the granules of metallic lead. According to the molten flow method, molten lead is introduced into a Barton pot and is violently agitated by agitating blades while supplying air, to effect oxidation, and fine powder of a mixture of lead oxide and metallic lead is recordered.
So-called lead powder obtained according to the above-mentioned methods is also called "lead suboxide" and in general, it has a composition represented by the following formula: EQU PbO.sub.x
in which x is a number of from 0.3 to 0.7. It is said that the lead powder is a composite or mixture of lead monoxide of the tetragonal system and metallic lead. This lead powder is most popularly used as the starting substance of an active material of a lead battery, and it is said that the lead powder is most excellent in properties among substances to be used for manufacture of active materials of lead batterys.
Also litharge (lead monoxide of the rhombic system) is broadly used as the starting substance of an active material of a lead battery. This lead monoxide is obtained by blowing oxygen or air into lead powder (lead suboxide powder) obtained according to the abovementioned methods and heating and oxidizing the lead powder at about 600.degree. C. Further, minium (Pb.sub.3 O.sub.4) is used as the starting substance of an active material. This lead oxide is prepared by blowing air into the above-mentioned lead powder and heating and oxidizing it at about 450.degree. C.
As will be apparent from the foregoing illustration, each of starting substances of active materials of lead batterys is prepared from metallic lead by dry oxidation thereof. These starting substances are still insufficient in the preparation process and in properties and characteristics.
In the art handling lead, it is very important that the working environment or living environment is not contaminated with lead dusts. If this requirement is not satisfied, it is not possible to conduct the preparation of lead compounds. In the steps of the above-mentioned process for manufacture of lead powder, gases containing lead dusts should inevitably be formed and discharged, and at the step of calcination oxidation of lead powder to litharge or minium, high temperature exhaust gases containing lead dusts should inevitably be generated. Accordingly, expensive dust precipitators should be disposed to collect lead dusts from these exhaust gases. Further, even if such dust collecting operation is conducted, it is difficult to collect lead dusts completely, and therefore, the problem of preventing the environmental pollution is left unsolved.
Further, each of conventional starting substances of active materials, such as lead monoxide and minium, has such a large particle size that the average primary particle size is in the range of from 1 to 10.mu., and it is not sufficiently satisfactory in the ratio (based on PbO) of utilization of an active material.
It has been desired to develop a lead battery having a high capacity and a light weight as a pollution-free battery for an automobile or operation car or for load levelling of power.